With the proliferation of wireless networks, today, it is possible to extend network coverage to wider areas and even reach remote locations wirelessly. The 4th Generation (4G) of cellular wireless standards such as LTE-Advanced (Long Term Evolution) and IEEE 802.16j aims at significantly improving the wireless communication further. The introduction of relay stations in such wireless networks is directed to improve cell edge user throughput and enhance coverage of the eNodeBs (base stations). Relay stations serve smaller coverage area than eNodeBs. An eNodeB transfers data to and from one or more relay stations, which in turn serve user terminals (UTs) located in their coverage area.
For transmitting data from the UTs to an eNodeB in the uplink, a UT sends the data via a relay station. In such a scenario, the relay station ensures the delivery of user data from the UT to the base station. In other words, the user data from the UT to be transmitted to the base station is buffered at the relay station serving the UT. Since, the base station is unaware of the number of UTs that have uplink data buffered at the relay station, it may not be able to reserve sufficient uplink resources for all the UTs as per their requirements. This can result in degraded quality of service.
In existing cellular systems, uplink buffer status reporting by UTs is quite prevalent. For example, in LTE, each UT transmits an uplink buffer status report to its serving eNodeB indicating a quantized amount of uplink data pending in the UTs' buffer for different logical channel groups. The purpose of this technique is to enable the eNodeB to give the requisite amount of uplink resources to the UTs.
Further, IEEE 802.16j/D5 (2008-05-30) describes that the exact single user information and the bandwidth requested need to be sent by the relay to the base station to enable the base station to schedule the user on the relay-user access link.
None of the foregoing techniques address issues related to uplink transmission from UTs to a base station using a relay station in a way that ensures optimal quality of service to the UTs with reduced overhead. Therefore, there exists a need for a method to uplink user data from user terminals to a base station via a relay station without the need to send the detailed information of the UTs yet ensuring that all the user terminals get acceptable quality of service.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.